Hello Philippe,

Thank you for posting into our community!

I have been looking into your question, however, on my side, I was not able to reproduce this behavior and the combo is closed without any errors in the DevTools Console.

Having this in mind, could you please provide a small working sample that demonstrates the behavior on your side?

Additionally, it is recommended to use the IgxSimpleCombo instead of modifying the IgxCombo with the following code:

public singleSelectionTask(event: IComboSelectionChangingEventArgs) {
    if (event.added.length) {
        event.newSelection = event.added;
    }
    this.combolistetache.close();
}

However, if you would like to use the IgxCombo instead, what I could suggest, in order to close the combo after selecting/deselecting an item, is using the owner argument which provides a reference to the owner component, i.e., the IgxCombo.

public singleSelectionTask(event: IComboSelectionChangingEventArgs) {
    ...
    event.owner.close();
}

Please test this approach on your side and let me know how it behaves.

Looking forward to your reply.

Sincerely,
Riva Ivanova
Associate Software Developer